Cellular/PCS ("wireless") telephone and communications networks rely upon a system of antennas for connecting cellular/PCS devices to the wireless networks. The antennas and related cellular/PCS devices send and receive radio frequency ("RF") signals between themselves. To optimize this communication, the cellular/PCS antennas are typically mounted on vertical poles that are situated at the top of tall masts, buildings or other structures. These mounting structures, along with the antenna and related hardware, are referred to in the art as "base stations."
As a result of its higher elevation, the antenna is better able to send and to receive an RF signal to and from a cellular/PCS device, i.e., the antenna's "view" of the signal from the cellular/PCS device is improved. The improved view of the antenna results from the fact that the antenna is positioned at an elevation above hills, buildings, trees and/or other such objects that may impede and/or obstruct the propagation of the RF signal.
The use of mechanical downtilt in an antenna mounting can prevent the RF signal emanating from the antenna from passing over a cellular/PCS device that is located near the antenna and can prevent RF signal interference between the relevant antenna and other cellular/PCS base stations. This enables the antenna's RF signal to be directed downwards toward cellular/PCS device users and away from other cellular/PCS base stations.
Typically, cellular/PCS base stations utilize antennas that are directed at a downtilt angle of 0.degree. to 10.degree. from the base station's horizontal axis and that are operated with a half-power beamwidth RF signal. As a result, the mechanical pointing mechanism for the antenna must be capable of providing downtilt adjustment tolerance of one degree (1.degree.) or less and providing an operator with a clear indication of such downtilt adjustment.
Mounting brackets for use with cellular/PCS antennas are well known in the art. Antenna manufacturers typically include hardware for mounting their antennas to poles and for adjusting the mechanical downtilt of the antenna. Because cellular/PCS antennas are often long and slender and mounted perpendicular to the base station's horizontal axis, prior mounting brackets typically secure the antenna to the pole using two separate, unconnected mounting brackets.
Typically, one of the brackets is attached to the antenna's upper end and the other bracket is attached to the antenna's lower end. The antenna's downtilt position is induced by pivoting the antenna around the lower mounting bracket. The top bracket can be used for moving the position of the upper end of the antenna about the lower bracket pivot point and as a means for locking the downtilt position of the antenna into the desired position.
There are several disadvantages associated with these prior art mounting assemblies. First, two separate, unconnected mounting brackets require vertical adjustment relative to each other based upon the length of the antenna and alignment of the azimuth rotation of each bracket to allow for an accurate and non-binding downtilt adjustment. In addition, once the antenna is attached to the lower mounting bracket, a second installation technician is required to hold the antenna in a proper, upright position while the primary technician attaches the upper mounting bracket to the antenna.
Prior art mounting brackets have primarily utilized either a "scissors"-type upper bracket or an upper bracket with an adjustable linear slot to adjust the downtilt position of the antenna. There are several disadvantages associated with each of these types of upper brackets. First, with respect to linear slot brackets, friction tends to make adjustment throughout the range of motion of the slot difficult and the linear slot assembly may bind as a result. Further, a linear slot assembly does not allow for exact, digital adjustment of an antenna's downtilt position. Next, with respect to scissors-type brackets, such brackets normally consist of at least three linkage parts in addition to the upper mounting bracket and, therefore, increase manufacturing and installation time and expense. Also, such brackets typically are adjusted and locked into position through the use of small pins or rods or by tightening the hinge pivot bolt. As a result, assembly and adjustment of these brackets is difficult and time-consuming.
Subsequently, there is a need for an antenna mounting assembly that allows for installation of an antenna by a single installation technician, that reduces that number of parts necessary to complete the installation thereby reducing manufacturing and installation time and expense, that can be modified easily to provide for either analog or digital adjustment of the antenna's downtilt position and that allows for non-binding, readily identifiable adjustment of the antenna's downtilt position.